MacDonald exercises take care of the left knee movement in the start up/backstroke. But it doesn't deal much with the downstroke. But that is where this movement in the video comes in - to reverse what has happened in the start up?
Yoda has made it very clear through the years on this forum - the knee movements in a swing accommodate, and are a result of, proper hip action in the framework of the tripod. Focus on proper hip movements, not the knees.
Linear Mode
